Carburetor



J. S. CARREY Nov. 25, 1952 CARBURETOR Filed Sept. 26, 1949 TIM mE N E WA.s.

w o Y I 6 n B ATTORNEY Patented Nov. 25, 1952 CARBURETOR John S. Carrey,St. Louis, Mo., assignor to Carter Carburetor Corporation, St. Louis,Mo., a corporation of Delaware Application September 26, 1949, SerialNo. 117,772

7 Claims.

This invention relates to carburetors for internal combustion engines,and consists particularly in a novel accelerating pump and fuel meterinmeans. This application is a continuation in part of my co-pendingapplication, Serial No. 674,876, filed June 6, 1946, now abandoned.Certain features disclosed, but not claimed herein, are claimed in acopending application, Serial No. 194,289, filed November 6, 1950 in thename of Henry Boller.

Automotive carburetors arev usually provided with accelerating pumps,the purpose of which is to supply an extra charge of fuel when needed,as for acceleration. Such pumps are usually operated by the throttle orbymanifold suction. Each type has advantages and disadvantages, thethrottle actuated pump having desirable positive action not attained bythe suction type, whereas the suction actuated pump is capable ofsupplying a pick-up or accelerating charge whenever needed, even thoughthe throttle valve is not moved. It has been found that a diaphragm typepump is more satisfactory than the piston type, since an imperfectpiston packing may result in loss of pressure or sticking of the pistonbut the diaphragm pump arrangements with which I am familiar other thanthe one disclosed in mycopending application, Serial No. 674,876, havenot provided for joint suction and manual operation of the samediaphragm by means of simple compact mechanism wholly concealed withinand protected by the normal wall structure of the carburetor.

An object of this invention is to providean improved arrangement wherebythe operation of the accelerating pump and metering pin are controlledeither by the throttle valve or by changes in suction, yet providing fora greater degree of flexibility in the interrelation of movement betweenthese elements, thereby to make their operation more nearly responsiveto engine fuel requirements.

More specifically, the object of this invention is to provide, in a pumpof the character mentioned, means whereby the throttle may be opened andthe metering pin elevated without necessarily causing a dischargemovement of the pump diaphragm until the manifold vacuum has beensufficiently reduced to justify a discharge movement.

Other objects and advantages of thepresent invention will appear readilyfrom the disclosure which follows, where read in connection with theaccompanying drawings, in which:

Fig. 1 is a side view and vertical section 2 through an automotivecarburetor, embodying one form of the invention, the parts being shownin idling positions.

Figs. 2 and 3 are detailed vertical sections taken at different anglesto the plane of Fig. 1 so as to illustrate, respectively, theaccelerating pump discharge passage and the main fuel nozzle.

Fig. 4 is a side view of a vertical section through an automotivecarburetor, embodying a modification of the invention.

Figs. 5 and 6- are fragmentary side views and vertical sections showingthe pump structure of Fig. 4 in different operative positions.

Figs. 7 and 8 are, respectively, a plan view and an elevation of theoperating link detail.

Referring first to Figs. 1 to 3, the carburetor l9 includes a mixturconduit ll formed with a series of Venturi tubes l2, centrally supportedin the conduit by a rib l3. Discharge of fuel mixture from conduit II iscontrolled by a throttle valve 14 mounted on a shaft I5. A suitablechoke valve (not shown) may be provided in the upper portion of themixture conduit. Mixture conduit II is flanged at its lower end, as atIt for attachment to the engine intake manifold (not shown). A constantlevel fuel bowl I! encloses a float l8 controlling a needle valve (notshown) for maintaining fuel at a constant level X-X.

A metering orifice element 2| controlled by a stepped metering pin 22 isprovided in the lower portion of bowl ll. Passages 23 and 24 connectelement 2| to main fuel nozzle 25 which discharges into the smallestVenturi tube l2, Fuel for idlingis supplied through passages 26 and 27to ports 28 adjacent and posterior to the edge of throttle I4 whenclosed.

A cavity 3! is formed in the lower wall of constant level chamber I7 andis closed on its outer side by a flexible diaphragm member 3'2, securedin place by a cap 33; Cavity 3i and diaphragm member 32 form a pumpingchamber which is connected to the fuel bowl ll by inlet passage 34controlled by inlet check valve 35. A passage 39, controlled by outletcheck valve 37, and restricted outlet nozzle 38 connect the pumpingchamber to mixture conduit II.

A tubular guide 49 extends upwardly'into constant level chamber [7 fromthe centralportion of pump chamber cavity 3| and slidably receives thediaphragmactuating stem M. A bracket 42 is secured to stem 4! andcarries metering pin 22 so that movements of the metering pin correspondto movements of the diaphragm. A second tubular guide 43 extendsvertically into constant level bowl I! and slidably receives a link 44having an offset portion 45 at its upper extremity with an aperturewhich slidably receives the upper extremity of stem 4|. A collar orwasher 45 keyed or otherwise lodged on stem 4| limits upward movement oflink 44 relative thereto. Link 44, at its lower extremity is connectedby a small link 4'! to an arm 48 rigid with throttle shaft l5, so thatupon opening movement of the throttle the diaphragm is forced upwardlyto inject a charge of accelerating fuel into the mixture conduit, andthe metering orifice 21 is simultaneously opened.

A coil spring 50 is compressed between the underside of diaphragm 32 andcap 33 and urges diaphragm 32 upwardly. Chamber formed between diaphragm32 and cap 33 is connected by a suction passage 52 to a port 53 openinginto the mixture conduit l l posterior to throttle l4, so that whenengine suction increases, diaphragm 32 is moved downwardly, compressingspring 50, and drawing a charge of liquid fuel from constant levelchamber l1 into pumping chamber 3|. Upon sufficient decrease of suction,spring 58 causes discharge movement of the diaphragm.

An adjustable limitation on the upward or discharge movement ofdiaphragm 32 relative to operating link 45 is provided by a stop collar54 which is secured to stem 4| above bracket 42. Such a limitation maybe necessary to obtain the desired mixture proportions under certainconditions. The stop also permits priming action of the pump in startingthe engine by operation of the throttle pedal.

It should be noted that the entire pumping and metering arrangement,with the exception of the lower extremity of link 44 and its operatingconnection to the throttle, is located wholly within the confines of theconstant level bowl. The mechanism is thus protected from dust and otherforeign material and does not interfere with the symmetrical, compactappearance of the carburetor.

Operation of the device is as follows: Fuel is drawn into pumpingchamber 3| by downward movement of the diaphragm to the position of Fig.1 upon increase in manifold suction. Thereafter, the diaphragm may moveupwardly to discharge fuel into the mixture conduit either upon openingmovement of the throttle through linkage 44 or upon expansion of spring58 when a drop in suction occurs and metering pin 65 moves accordingly.The liquid fuel in the pumpin chamber acting against the diaphragmprovides a cushioning Ol' dashpot action against too abrupt openingmovement of the metering pin and throttle. The manual and suctionoperations complement but do not interfere in any way with each other.

Referring now to Figs. 4 through 8, in which a modified form of theinvention is illustrated, the carburetor 56 includes a mixture conduit51 formed with Venturi tubes 58, centrally supported in the conduit. Athrottle valve 68 mounted on a shaft 6| controls the discharge of fuelmixture from mixture conduit 51. A flange 52 is formed at the lower endof mixture conduit 51 for attachment to the engine intake manifold. Theconstant level fuel chamber 63 includes a float controlled needle valve(not shown) for maintaining fuel at a constant level.

A metering orifice element 64, controlled by a stepped metering pin 65is positioned in the lower portion of constant level chamber 63.Passages 4 66 and 6! connect the metering orifice element with the mainnozzle passage 68.

A depression 69 is formed in the bottom wall of constant level chamber63 and is closed on its inner side by a diaphragm member 10, secured inplace by an inverted cup H, the cup and diaphragm cooperating to form apumping chamber I2 which communicates with constant level chamber 63 bymeans of an opening 13 in the upper portion of cup H. An annular screen14 is mounted on cup H to filter impurities from fuel entering thepumping chamber. A passage [5 controlled by an outlet check valve 16 andhaving a restricted outlet nozzle 17 connects pumping chamber 12 withfuel mixture conduit 51. A tubular guide 13 extends upwardly intoconstant level chamber 63 from the central portion of cup 1| andslidably receives the diaphragm actuating stem 19. Stem 19 is formedwith a groove which receives and prevents upward movement of a cupped,horseshoe washer 8| relative to the stem. A coiled compression spring 82is received about guide 18, its lower end abutting a boss 83 on theupper surface of cup H and its upper end abutting washer 8| so as totend to urge stem 19 and diaphragm 10 upwardly.

A chamber 84, formed between bowl depression 89 and diaphragm 10 isconnected by a suction passageway 85 with a suction port 86 in themixture conduit wall posterior to the throttle, so that diaphragm 10moves responsive to variations in manifold suction.

A second vertical guide 88 of rectangular cross section extends intoconstant level chamber 83 adjacent guide 18 and slidably receives agooseneck link 89 having at its upper end an offset portion 90 formedwith a horizontal ledge 9|. Ledge 9| has an aperture in its outer endportion which slidably receives diaphragm stem 19. The upper end portionof stem 79 is of slightly less diameter than the remainder of the stemto form a shoulder 92, the function of which is described below. Anangular bracket 93 has an aperture 94 at one end for slidably receivingthis narrow portion of stem 79, and has a pin 95 at its other end forattachment of metering pin 65. The bracket normally seats on the upperportion 9| of link 89 or stem shoulder 92, whichever is uppermost anditself seats a coiled compression spring 96, retained on stem 19 by akeyed or otherwise retained washer 91. Link 89 at its lower end isconnected by a small link 98 to a arm 99 rigid with throttle shaft 8|,so that upon opening movement of the throttle, link 89 moves upwardly,carrying with it bracket 93 and resiliently, by means of spring 98,urging stem 19 and diaphragm l0 upwardly, as in Fig. 6. When thedecrease in suction occurs at a greater rate than opening of thethrottle valve, shoulder 92 of stem 19 engages bracket 93 to furtherelevate metering pin 65 as in Fig. 5. When suction remains high, eventhough the throttle is being opened, diaphragm l0 prevents upwardmovement of stem 19; upward movement of link 89 by the throttle elevatesbracket 93 and the metering pin while compressing spring 98, as in Fig.6. During closing movement of the throttle, spring 98 again urgesbracket 93 downwardly against either shoulder 92 or ledge 9|, whicheveris uppermost, so that lowering of the metering pin is limited by one ofthese elements.

Operation of the device is as follows: Fuel is drawn into the pumpingchamber by downward movement of the diaphragm resulting from increase inmanifold suction. Thereafter, the .diaphragm may move upwardly eitherupon a drop in suction or upon opening movement of the throttle throughlinkage 89, upward movement of ledge 9| being transmitted to stem 19 viabracket 93, spring 88, and washer 91. The position of b k 93, a d c ns uf mete in p n 65, is governed by whichever of the elements, ledge 9! orshoulder ,92, is uppermost, downward or closing movement of the meteringpin being thereby limited by the amount of suction or the degree ofopening of the throttle.

It should also be noted in this connection that by shortening the lengthof travel of link '98 this device may be constructed so that thethrottle connection cannot fully elevate the metering pin, the lastportion of metering pin elevation and final movement .of the diaphragmin the pumping direction being produced by a further decrease insuction.

The invention may be modified in various respects as will occur to thoseskilled in the art and the exclusive use of all modifications as comeswithin the scope of the appended claims is contemplated.

I claim:

1. In a carburetor, a downdraft mixture conduit having a throttletherein, a constant level fuel bowl adjacent the same, a recess in thebottom wall of said bowl, a horizontal diaphragm extending across saidrecess and dividing the same into an accelerating pump chamber abovesaid diaphragm and a suction chamber below said diaphragm, saiddiaphragm being sealingly secured over said recess, inlet and outletpassages connecting said pump chamber, respectively, to said bowl andsaid conduit, a suction passage connecting said suction chamber to saidmixture chamber below said outlet passage, a spring urging saiddiaphragm upwardly in opposition to suction thereon, a tubular guideextending vertically from such recess into said fuel bowl above thenormal fuel level therein, an operating stem centrally secured to saiddiaphragm and extending upward through said guide and terminating withinsaid bowl, a second tubular guide extending vertically into said bowl, asecond stem having an offset portion slidably carried by said operatingstem, a link connecting said second stem to said throttle, and spacedabutments on said diaphragm operating stem forming a lost motionoperative connection between said second stem and. said throttle andsaid first stem and said diaphragm.

2. In a carburetor, a downdraft mixture conduit having a throttletherein, a constant level fuel bowl, an enclosed depression in thebottom of said bowl, a diaphragm dividing said depression into a pumpchamber and a suction chamber, inlet and outlet passages, respectively,connecting said pump chamber to said bowl and said conduit, a suctionpassageway connecting said suction chamber to said conduit posterior tosaid throttle, an operating stem attached to said diaphragm and having aresilient, one-way operating connection with said throttle, a meteringorifice element within said bowl, a metering pin slidably andresiliently secured to said stem for elevation therewith upon reductionsin suction and for elevation with said one-way connection upon openingmovements of said throttle.

3. In a carburetor, a downdraft mixture conduit having a throttletherein, a constant level fuel bowl adjacent the same, a depression inthe bottom wall of said bowl, a diaphragm sealingly said suction chamberto said mixture chamber.

below sa d out t pas age, a .fue p ssage connecti s sai bowl w th saicondu t, a me e ing orifice e em nt f r o trollin the flow of fuelthrough a pas e, a m tering p n in aid orifi e, a tubular guideextending vertical-y from said. ,Gup, an operating stem centrallysecured .to said diaphragm and extending upward through said guide andterminatingwithin said bowl, a spring on said guide for urging said stemupwardly in opposition to suction ,on said diaphragm, an u wardly facingshoulder on said stem, a second guide extending vertically into saidbowl, av link slidable in said second guide, said link at its lowerextremity being operatively connected to the throttle and having at itsupper extremity a horizontal ledge slidable on said operating stem, abracket slidably carried by said stem above said. shoulder and alsoabove said ledge, and a second spring on said stem for urging saidbracket down-- ward, said metering pin being attached to said. bracketfor movement therewith.

4. In a carburetor, a mixture conduit having a throttle therein, a fuelbowl, an accelerating pump pressure chamber formed in a wall of saidbowl, a diaphragm sealingly closing said chamber, inlet and outlet fuelpassages, respectively, connecting said chamber to said bowl and saidconduit, a suction chamber formed on the outer side of said diaphragmand a suction passage con necting the same to said conduit, a pair oftubular guides extending upwardly into said bowl, an operating stemextending from said diaphragm through one of said guides, a linkconnected to said throttle and extending through the other guide andhaving a lost-motion, operative connection to said stem, and a springconstantly urging said diaphragm in opposition to the suction effectthereon for causing pump discharge upon a drop in suction, said stembeing located wholly within the confines of said bowl and said linkbeing wholly within said bowl except for the extremity thereof connectedto said throttle.

5. A carburetor as specified in claim 4 further including a meteringorifice element within said bowl and a metering pin carried by said stemabove the guide receiving the same and wholly within the confines ofsaid bowl.

6. In a carburetor, a downdraft mixture conduit having a throttletherein, a constant level fuel bowl adjacent the same, a recess in thebottom wall of said bowl, a flexible diaphragm sealingly secured overand forming the outer wall of said recess, inlet and outlet passages,respectively, connecting said recess to said bowl and said conduit, atubular guide extending vertically into said bowl to a point above thenormal fuel level therein, an operating stem centrally secured to saiddiaphragm and extending upwardly through said guide and terminatingwithin said bowl, a second tubular guide extending vertically into saidbowl, and a link connected at its lower extremity to said throttle andslidably received in said second guide, said link having an oif-setportion and said stem having an abutment near its upper extremityforming a one-way connection between the two whereby opening movement ofsaid throttle moves said diaphragm upwardly to inject an acceleratingcharge into said conduit.

7. In a carburetor, a mixture conduit having a throttle therein, aconstant level fuel bowl, a wall of said bowl having restricted,oppositely cupped parts forming a chamber, a diaphragm mounted betweensaid cupped wall parts and forming a pump chamber and a suction chamber,restricted inlet and outlet passages, respectively, connecting saidpumping chamber to said bowl and said conduit, a suction passageconnecting said suction chamber to said conduit posterior to saidthrottle, an actuating stem projecting from said diaphragm into saidbowl, a guiding and sealing sleeve projecting from the inner of saidcupped wall parts inwardly along said stem, an operating connectionbetween said throttle and said stem inwardly of said sleeve, a meteringorifice element within said bowl, a metering pin cooperating with saidorifice element, and

JOHN S. CAR/REY.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,109,260 Chandler et a1 Feb. 22,1938 2,145,672 Udale Jan. 31, 1939 2,186,480 Ensign Jan. 9, 19402,207,456 Cofiey July 9, 1940 2,271,116 Bracke et al. Jan. 27, 19422,299,872 Ball Oct. 27, 1942 2,312,817 Heftler Mar. 2, 1943 2,328,604Bicknell Sept. 7, 1943 2,340,820 Moseley Feb. 1, 1944

